The Collaborative International Dictionary of English v.0.48:

Strait \Strait\, n.; pl. Straits. [OE. straight, streit, OF.
   estreit, estroit. See Strait, a.]
   1. A narrow pass or passage.
      [1913 Webster]

            He brought him through a darksome narrow strait
            To a broad gate all built of beaten gold. --Spenser.
      [1913 Webster]

            Honor travels in a strait so narrow
            Where one but goes abreast.           --Shak.
      [1913 Webster]

   2. Specifically: (Geog.) A (comparatively) narrow passageway
      connecting two large bodies of water; -- often in the
      plural; as, the strait, or straits, of Gibraltar; the
      straits of Magellan; the strait, or straits, of Mackinaw.
      [1913 Webster]

            We steered directly through a large outlet which
            they call a strait, though it be fifteen miles
            broad.                                --De Foe.
      [1913 Webster]

   3. A neck of land; an isthmus. [R.]
      [1913 Webster]

            A dark strait of barren land.         --Tennyson.
      [1913 Webster]

   4. Fig.: A condition of narrowness or restriction; doubt;
      distress; difficulty; poverty; perplexity; -- sometimes in
      the plural; as, reduced to great straits.
      [1913 Webster]

            For I am in a strait betwixt two.     --Phil. i. 23.
      [1913 Webster]

            Let no man, who owns a Providence, grow desperate
            under any calamity or strait whatsoever. --South.
      [1913 Webster]

            Ulysses made use of the pretense of natural
            infirmity to conceal the straits he was in at that
            time in his thoughts.                 --Broome.
      [1913 Webster]

WordNet (r) 3.0 (2006):

straits
    n 1: a bad or difficult situation or state of affairs [syn:
         pass, strait, straits]
    2: a difficult juncture; "a pretty pass"; "matters came to a
       head yesterday" [syn: pass, head, straits]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "straits":
   arm, armlet, bay, bayou, belt, bight, bind, boca, broken fortune,
   clutch, complication, cove, creek, crunch, difficulties, distress,
   embarrassing position, embarrassment, estuary, euripus,
   fine how-do-you-do, fjord, frith, genteel poverty, gulf, gut,
   harbor, hard pinch, hardship, hell to pay, hobble, hot water,
   how-do-you-do, imbroglio, impecuniosity, impecuniousness, inlet,
   insolvency, jam, kyle, light purse, loch, mess, mix, morass, mouth,
   narrow, narrow means, narrow seas, narrows, natural harbor,
   parlous straits, pass, pickle, pinch, plight, poorness, poverty,
   predicament, pretty pass, pretty pickle, pretty predicament,
   quagmire, quicksand, reach, road, roads, roadstead, scrape,
   slender means, slough, sound, spot, squeeze, stew, sticky wicket,
   strait, straitened circumstances, swamp, tight spot, tight squeeze,
   tightrope, tricky spot, unholy mess, unprosperousness,
   voluntary poverty, vows of poverty